No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Design of Compact Planar Filters Miniaturization Challenges
Abstract
The filter's reduction in size becomes a significant difficulty because it frequently has a considerable impact on the wireless system's overall dimensions. This chapter's goal is to introduce fresh ideas that have been made to shrink filters that yet perform admirably. Then, a variety of filters that have been created are revealed. Some microstrip filters are miniaturized using coupled lines, quasilumped elements, and stub topology, and other structures are based on resonators. The structures presented are optimized and validated for different frequency bands (GPS, DCS, ISM, mobile phone, WIMAX). The filter is introduced in its overall context. Using ADS, HFSS, and CST-MWS, a full-wave electromagnetic analysis has been successful in assessing the electrical performances of the suggested structures.
... To use any of these methods, a designer must have a solid understanding of microwave technology, electromagnetic theory, antenna theory, wave propagation, etc. In light of this, the design of microwave devices is considered to be a challenging task due to various factors such as complexity of optimization [8,30], miniaturization and size constraints [31][32][33], manufacturability and fabrication challenges [1,8,34]. Since conventional techniques are hindered by all of these difficulties, unconventional techniques must be explored. ...
Microwaves and RF technology and their components like filters, antennas, etc. are commonly used in wireless networking and communication systems, wireless security systems, radar systems, and environmental remote sensing. In this paper, a fast and effective procedure has been proposed for microstrip filter design using a genetic algorithm (GA) with a transmission line model (TL). GA is modified to be highly efficient and accurate by encoding the topology. For the fixed filter topology, the electrical parameters of the filter are encoded in a single chromosome. To make the proposed procedure fast and effective, a transmission line model has been employed to compute the fitness value in GA. To demonstrate the effectiveness of the proposed procedure, a wideband second-order bandpass filter with a center frequency of 2.3 GHz is examined with a pair of short-circuited stubs and a pair of open-circuited stubs. The optimized design is validated using full-wave methods (MoM and EM simulator CST). The results show a low insertion loss of 0.1 dB and return loss better than 30 dB and a wide bandwidth of 46.95% with − 3 dB cutoff frequencies at 1.76 GHz and 2.84 GHz.
... Therefore, small-size, low-cost, as well as wide stopband characteristics with suitable frequency selectivity BPFs in transmitters and receivers are essential. Planar technology has many advantages that meet most of the filter requirements and provides a good tradeoff between performance, size, and cost [1,2]. Moreover, planar technology provides topological flexibility as well as adequate manufacturing control that leads to significant cost reduction. ...
A new compact wideband filter is introduced to address the requirements of recent communication and radar systems. The filter is based on a quarter-wavelength short-circuit coupled stepped impedance resonator (SIR). The analytical solution shows that the suggested SIR resonator provides a compact size and a wide stopband response, which are essential features in many wireless communication systems. The analytical results also reveal that increasing the impedance ratio of the SIR extends the stopband by increasing the first spurious response and reducing its total length. A compact two-coupled short-circuit SIR filter is designed at 1.23 GHz. The design approach is validated using an ideal transmission line modeling analysis and electromagnetic simulation using CST Microwave Studio 2021. The proposed structure is shown to be flexible, allowing the achievement of a relative bandwidth as low as 5% and as high as 50%. A four-resonator filter is designed by cascading two stages of the designed two-coupled short-circuit SIR filter, which are coupled through a quarter-wavelength line. The simulation results illustrate that the suggested structure can be used to design a filter with any number of resonators. The filter is implemented using a high-resolution LPKF laser machine on Rogers RT/duroid 6010.2LM material with a thickness of 0.635 mm. From the measurements, the bandwidth is found to be 390 MHz and centered at 1325 MHz (29.4% relative bandwidth) and the insertion loss is 1.3 dB. The simulation and experimental results verify the proposed approach and indicate the potential of this component in meeting the design requirements of next-generation microwave circuits related to flexibility and size-compactness.
This paper presents a new miniature Microstrip Bandpass Filter optimized and validated for DCS (Digital Cellular System) Band. The proposed filter is based on a Microstrip resonator. Each port has a step impedance feed line that can be used to adapt the filter's input impedance to the characteristic impedance Z0. The suggested filter is installed on a low-cost FR-4 substrate with a dielectric constant of 4.4, a thickness of 1.6 mm, a loss tangent tan (δ) = 0.025, and a metal thickness of t = 0.035 mm. It has a bandwidth of 1.68GHz to 2.05GHz. Two electromagnetic solvers are used to optimize and validate this filter. The whole dimensions of the final circuit are 33.6x40 mm ² .
This filter is suitable for mobile communication .
In this paper, a novel compact band pass filter (BPF) is proposed for global positioning system (GPS) applications. The proposed filter which is based on a microstrip resonator is mounted on a low cost RO4000 substrate with a dielectric constant εr=3.5, a thickness h=1.542 mm, a loss tangent tan (δ)=0.0027. It has a bandwidth from 1.55 GHz to 1.72 GHz. This filter is optimized and validated by using two electromagnetic solvers. The area occupied by this BPF is 33.6×41.24 mm2. The final circuit is a low cost BPF and can be associated with passive and active circuits due to the miniature dimensions.</span
This paper presents design of dual-band bandpass filter by integrating conventional quarter-wavelength short circuit stubs bandpass filter with U-shaped defected microstrip structure notch filter. Based on the parametric analysis, it is found that high attenuation level can be achieved by using two U-shaped defected microstrip structure separated by specific distance. The designed circuit simulated using advanced design system and fabricated based on Roger 4350B. The simulation results are in good agreement with measured results. The designed filter covered two pass bands centered at 2.51 GHz and 3.59 GHz with 3-dB fractional bandwidth of 15.94% and 15.86%, respectively, return losses better than 15 dB, and insertion losses better than 1 dB. The designed device can be used for wireless communication applications such as WLAN and WiMAX.
This paper presents the design of a compact bandpass filter based on two identical rectangular resonators and is implemented on microstrip technology for Wi-Fi and bluetoothapplications. To reduce the size of the filter, the defected microstrip structure (DMS) technique is proposed. This technique consists of etching slots in the rectangular resonator, which results in a change in the line properties and increase of the effective inductance and capacitance. This feature is used for miniaturization. The designed filter has a compact size (6.82x8.3) mm² with a low insertion loss of-0.1 dB and a good return loss of-36 dB. The simulation results are realized using the (computer simulation technology) CST Microwave software.
This paper presents a quasilumped Microstrip structure High Pass Filter having a cutoff frequency 2.5 GHz. The quasilumped elements are used with the objective of obtaining the behavior of a high-pass filter with high bandwidth, reducing the size of the filter and improving the electrical performances. The proposed filter is designed on an FR-4 substrate having a thickness of 1.6mm, a dielectric permittivity constant of 4.4 and loss tangent of 0.025. The proposed filter is optimized and validated by using three electromagnetic solvers (ADS, HFSS and CST-MWS).The whole area of the proposed circuit is 19 x 16 mm 2 .
This paper presents an inter-connected side-shorted coupled-line resonator topology as a base cell. The base cell is built from two single-shorted quarter-wavelength coupled-line sections, connected in series to give a half-wavelength coupled-line that creates a single resonance of bandpass filter response. Higher-order bandpass filter is produced by adding new single-shorted coupled-line sections, cascaded in an inter-connected manner to the base cell. This new topology creates a unique arrangement that caused cross coupling effects between the resonators, resulting to the occurrence of transmission zeros that lead to the improvement of selectivity of the higher order bandpass filter response. For validation of concept, 2nd and 3rd order bandpass filters were fabricated using microstrip technology on Roger 3210 substrate with parameter of Ɛr = 10.2, h = 1.27 mm and tan δ = 3x10-3. The filters were measured and the results show good agreement with simulation results.
This paper presents the design and the comparison of an Open circuit Microstrip Band Stop Filter using two simulators: CST microwave studio and Advanced design system (ADS). This filter is designed on central frequencies f1=2GHz and f2=4.5GHz. The simulation shows a coincidence between the S-parameter results for the proposed band-stop filter. The rejection band of the band-stop filter is about 76%, else the filter has 25 dB return loss, which characterized by good selectivity.
This letter presents a new circuit of the band-pass filter designed by using microstrip technology. Based on complementary split ring resonator and various series of optimization technic and a specific design method, a miniature band-pass filter with excellent electrical performances is achieved. First of all, the metamaterial unit cell is studied to obtain a desired resonant frequency and it is implemented in the ground plan in order to increase the characteristics of the bandpass behavior and decrease its operating frequencies. This proposed circuit is designed on an FR-4 substrate having a relative permittivity of 4.4 tangential losses of 0.025 and thickness of 1.6 mm. This filter is developed by using CST Microwave. The obtained features allow this filter to be used in diverse wireless applications such as IMT-E and WiMax.
p>This paper proposes a quasi-elliptic band pass filter in substrate integrated waveguide (SIW) by using cross coupling technique to produce transmission zeros (TZs) at both side. Finally, a fourth pole SIW quasi-elliptic filter at 5.75 GHz is designed in single layer substrate. Simulation results show that the filter has a center frequency of 5.75 GHz with the bandwidth of 100 MHz. The minimum insertion loss in the passband is 0.3 dB, and the return loss is better than 20 dB. Due to the TZs, the SIW filter has rapid transition performance at both lower and upper sidebands, good selectivity is achieved, while the SIW filter presents a very compact implementation and good
spurious rejection.</p
Complementary Split Ring Resonators were used embedded in a substrate integrated waveguide to generate passband charateristics in X-Band. Based on a parameter study with an electromagnetic commercial software, the characteristics of double and quadruple CSRRs according the reflection and transmission factor were observed. The computer simulation showed, the bandpass filter worked in the frequency range 8.12-8.63 GHz and 8.11-8.63 GHz for double and quadruple CSRR, respectively. The insertion loss was 0.12 dB and 0.015 dB. The measurement mit a vector network analyzer verified the simulation results. The frequeny range measured was 8.12-8.67 GHz and 8.12-8.61 GHz for double and quadruple CSRRs, respectively. The measured insertion loss was 0.25 dB and 0.2 dB. © 2019 Institute of Advanced Engineering and Science. All rights reserved.
In this paper, a new bandpass filter is designed using two open-loop resonators with polygonal forms. The use of polygonal forms leads to compact size and broad bandwidth behavior. The overall filter dimensions are 8×16 mm2, which correspond to 0.4λg × 0.2λg using a substrate with Rogers Ro 3010 with a relative permittivity of 10.2 and a thickness of 1.5 mm. The resulting filter exhibits enhanced passband behavior with two transmission zeros. The resulting passband has a centre frequency of 2.40 GHz, and a bandwidth of 230 MHz and fractional bandwidth (FBW) of 10%, with return loss of about −26 dB and insertion loss equal to −0.8 dB. The locations of the two transmission zeros are at 2.176 GHz and 2.638 GHz, which means that there is a sharp cut before and beyond the passband. The simulation and performance evaluation of the proposed filter were carried out using Microwave Studio Suite (MWS) Computer Simulation Technology (CST). The resulting performance of the proposed filter makes it very desirable for Bluetooth and WLAN applications (IEEE 802.11n).
In this paper, a hairpin bandpass filter using coupled lines is designed for satellite applications. Initially, a conventional microstrip parallel coupled line filter is modified as hairpin based folded coupled line filter that works in S-band between 2-4GHz. The proposed filter is designed for the seventh order coupled line and its filter characteristics are analyzed. The idea of folded coupled lines are used for designing the ninth order folded coupled line filter which operates in 2.8GHz and the S-parameter results of filter are also discussed. The proposed seventh and ninth order filter has reduced insertion loss and high performance.
This paper presents two dual-mode rectangular ring resonators, designed at RF frequency above 20 GHz for bandpass filter applications. The first resonator is designed at 20 GHz using single layer microstrip technology, on Rogers Duroid TMM10 substrate with the following characteristics; relative dielectric constant (εr) = 9.2, substrate thickness (h) = 1.270 mm, dielectric loss tangent (tan δ) = 0. The second resonator is built using multilayer CMOS technology at 75 GHz. The resonator is simulated using fluorinated silicon glass (FSG) and silicone rich oxide (SRO) with relative dielectric constant (εr) equals to 3.7 and 4.2 respectively. Both filter designs are built using full-wave electromagnetic simulation tool. For filter design using microstrip technology, the return loss is found at 9.999 dB and the insertion loss is at 3.108 dB while for filter design using CMOS technology, the return loss is found at 11.299 dB and the insertion loss at 0.335 dB. Both results had shown good passband performance with high rejection level at the out-of band. © 2018 Institute of Advanced Engineering and Science. All rights reserved.
A new technique is developed for designing a composite microstrip bandpass filter (BPF) with a -3dB fractional bandwidth of more than 100%. The BPF is suitable for ultra-wideband (UWB) wireless communications. The design utilizes embedding individually designed high-pass structures and low-pass filters (LPF) into each other, followed by an optimization for tuning in-band performance. The stepped-impedance LPF is employed to attenuate the upper stop-band and quarter-wave short-circuited stubs are used to realize the lower stop-band. The filter had a good performance, including an ultra-wideband bandpass (3-10 GHz), a small size, low insertion loss, return loss better than 18 dB from 3.8 GHz to 9.3 GHz and sharp rejection. The filter also demonstrated an UWB reject band from 11.4 GHz to more than 20 GHz at -20dB.
Index Terms—Bandpass filters, microstrip lines, microstrip filters, ultra-wideband, wideband filters.
A compact dual-band microstrip bandstop filter (BSF) is presented. It combines a conventional open-stub BSF, a spurline, and two embedded open stubs. This BSF is simulated and fabricated. It generates two stopbands around 2.0GHz and 3.0GHz without increasing circuit size, compared with the conventional BSF.
A compact dual-mode microstrip bandpass filter using geometrical slot is presented in this paper. The adopted geometrical slot is based on first iteration of Cantor square fractal curve. This filter has the benefits of possessing narrower and sharper frequency responses as compared to microstrip filters that use single mode resonators and traditional dual-mode square patch resonators. The filter has been modeled and demonstrated by Microwave Office EM simulator designed at a resonant frequency of 2 GHz using a substrate of ε_r=10.8 and thickness of h= 1.27 mm. The output simulated results of the proposed filter exhibit 22 dB return loss, 0.1678 dB insertion loss and 12 MHz bandwidth in the passband region. In addition to the narrow band gained, miniaturization properties as well as weakened spurious frequency responses and blocked second harmonic frequency in out of band region have been acquired. Filter parameters including insertion loss, return loss, bandwidth, coupling coefficient and external quality factor have been compared with different values of perturbation dimension (d). Also, a full comparative study of this filter as compared with traditional square patch filter has been considered.
In this paper, a simple hexagonal wideband microstrip bandstop filter with an open-end stepped impedance stub has been proposed for the rejection of WLAN and WiMAX bands. Controlling the dimensions of the shunt open-end stepped impedance stub, the rejection bandwidth and the level of rejection can be controlled. The structure is very simple and is also easy to fabricate. The final filter structure provides a stop band that extends from 3.19 GHz to 5.36 GHz within and more than -20dB rejection and hence it can reject the 3.5 GHz WiMAX bands and 5.2 GHz WLAN frequency bands. The simulated response has been validated after comparing it with the measured data.
In this paper, a new method to design a dual band bandpass filter (BPF) is presented. This method is based on a simple principle: different substrates (dielectric constants) will result different resonant frequencies for a resonator. The basic structure of this method is studied and then a planar band pass resonator is designed to utilize in this structure. Response of the proposed dual layer filter is tuned using resonator shifting and resonator scaling. In addition to improve the filter response, resonator shifting improves the filter size. The final structure is designed, fabricated and measured and simulation results are in good agreement with measured values. The central frequencies of this dual band BPF are f1=3.85 GHz and f2=5.3 GHz and a deep transition zero at 4.57 GHz, guarantees isolation between passbands.
Broadband bandpass filters based on open complementary split ring resonators (OCSRRs) coupled through admittance inverters, and implemented in microstrip technology, are reported. As compared to other broadband filters based on open split ring resonators (OSRRs), ground plane etching is not necessary in the proposed filters. The selectivity of the filters at the upper transition band is improved thanks to the presence of a controllable transmission zero. To demonstrate the potential of this approach, two illustrative prototype devices have been designed and fabricated.
This paper proposes asymmetrical step-impedance resonators bandpass filters (ASIRs) for suppressing a wide stopband, ensuing in size reduction and ease of fabrication. The filters have been designed at the operating frequency around 2.0 GHz using half-and quarter-wavelength asymmetrical step-impedance resonators. The concept of existent odd- and even-mode characteristics is used to approve the proposed filter structure. The filter can not only suppress the unwanted signals more than 10f0, but also produce low passband insertion loss and high return loss. A good agreement is obtained between the simulation and measurement results.
A new technique for designing compact, band-pass filters of arbitrary orders is presented in this paper. The proposed approach is based on the design and optimization of a second order band-pass filter, which acts as the unit cell of a higher order filter. This unit cell is composed of slow-wave transmission line resonators, separated from one another by an inductive impedance inverter network. For applications requiring a narrow-band filter response, this unit cell is capacitively coupled to the outside world to increase the loaded quality factor of the resonators and achieve a narrower bandwidth. This mechanism provides a simple method of controlling the bandwidth and frequency response of the filter. Two different cascading topologies are used to achieve filters with either even (N = 2, 4, …) or arbitrary orders (N=2, 3, 4, …).
A bandpass filter (BPF) using CPW combined with microstrip is proposed. The target BPF is composed of two element filters built from combined CPW and microstrip structure. The design of element filter is based on the lumped elements approach with each circuit component built from a CPW or microstrip. In the circuit model, transmission zeros are created by the passband edges to enhance the signal selectivity. The element filter's characteristics are analyzed by the lumped L-C circuit model. Experiment is conducted, and a good agreement is observed between the measurement and simulation.
This paper presents a quasilumped microstrip structure highpass filter having a cutoff frequency 1.5 GHz. The quasilumped elements used for this design have their size smaller then the quarter of the guided wavelength at the operating frequency. The proposed designs is a three pole filter, consisting of short circuit stub transmission line and inter digital capacitors on a commercial substrate having relative dielectric constant 4.7 and 1.6 mm of thickness. A sample filter is designed based upon the theory presented and it has been simulated with the S-parameters using IE3D software.
This paper reports a wide bandwidth planar bandstop filter with improved RF characteristics. The proposed filter on alumina is realized incorporating tapped open stub along with spurline topology. Further, stepped impedance resonator (SIR) approach has been introduced in the tapped stubs to achieve wider band performance with improved selectivity. The proposed topology effectively controls the transmission poles. Fabrication of this BSF has been carried out on glass substrate showing minimal effect of permittivity variation on bandwidth performance. This validates the applied approach with achievable bandwidth of more than 100% ranging from S- to Ku-band. Close agreement with simulation and practical results have been demonstrated with measured insertion loss of less than 1 dB and attenuation loss better than 30 dB at C-band.
In this research article, single pole bandpass filter using stair-step patch topology based on symmetrical and asymmetrical step impedance resonators has been designed for industrial, scientific and medical (ISM) band application. This filter has been modeled by Microwave Office simulator using RT/Duroid substrate constant of 10.8, the substrate thickness of 1.27mm, loss tangent of 0.0023 and copper metallization thickness of 0.035 mm. To enhance the stopband levels of filter response, two microstrip bandpass filters have been designed as two-pole configurations based on edge, and cross-coupled stair-step patch resonators using the same simulator tool and substrate specifications. The proposed filters have compact sizes of (0.311 λgo x 0.233 λgo) for single pole filter, (0.578 λgo x 0.24 λgo)for two-pole edge coupled filter and (0.566 λgo x 0.234 λgo)for two-pole cross-coupled filter designed at center frequencies of 2.4, 2.46 and 2.41 GHz respectively. These filters have interesting insertion loss and return loss magnitudes, narrow band frequency responses, second harmonic suppression and good stopband levels. Apart from ISM band applications, the proposed filters can be adopted in WLAN systems and Bluetooth applications for short range devices. The experimental results for designed filters are of good consistency with the simulations.
This book describes the basic theory of microwave resonators and filters, and practical design methods for wireless communication equipment. Wireless communication is rapidly gaining in importance in our modern information society. Mobile communication equipment is required to be more compact, lighter weight, to have longer operating times, and be battery operated for portability. The microwave resonators and filters described in this book provide a basis for realizing all these requirements. From the basic theory to applications, the text enables the reader to understand the key role played by microwave resonators and filters. Superconducting devices and micro-electromechanical devices are also described. The sections on design theory will be especially informative for microwave researchers and engineers.
In this article, A compact size band pass filter based on octagonal resonators is presented to give sharp response at desired frequency bands along with very low insertion loss. The proposed filter structure is composed of octagonal microstrip resonators, backed by Quasi-Yagi slots 'Quasi-Yagi Defected Ground Structure' (Quasi-Yagi-DGS). By controlling the electrical coupling between the octagonal-strip and the Quasi-Yagi-DGS, the bandpass filter's stopband is optimized for better rejection. The proposed BPF has low insertion loss and compact size because of the slow-wave effect. Meanwhile, sharp rejection bands induced by the presence of two transmission zeros. The simulated center frequency and passband insertion loss are 2.4 GHz and 0.6 dB, respectively.
In this letter, a compact wideband microstrip filter using a multiple-mode resonator (MMR) is present. The basic filter is composed of only one resonator with two symmetrical connecting lines. The resonator operates as not only a resonant element but also an open stub. By properly adjusting the lengths of the stub, the first three resonant modes of this MMR can be evenly allocated within the 4.8-to-10.2 GHz wideband while the 4th resonant frequency is raised above 13 GHz. It results in the formulation of a novel WMBF with compact-size and widened upper-stopband. Simulated and measured results are found in good agreement with each other, showing improved WB bandpass behaviors with the insertion loss lower than 0.5 dB, return loss higher than 12 dB, and maximum group delay variation less than 0.5 ns.
The existence of WLAN Application over Ultrawide Band Spectrum becomes a challenge for development of UWB Applications. Hence, in this paper, an ultra wideband bandpass filter (UWB-BPF) with notched band at 802.11a Frequency Spectrum is proposed. The proposed filter is designed by using multimode ring resonator. The multimode ring resonator is represented by rectangular ring which is connected to the interdigital capacitor. The proposed filter is printed on the Duroid substrate with relative permittivity and thickness of 2.2 and 1.6 mm, respectively. The designed filter occupies the area of 36 mm × 16 mm. The proposed filter characteristics are investigated numerically and experimentally in terms of return loss, insertion loss, surface current, phase and group delay. From the numerical analysis, it shows that the proposed filter has a pass-band at frequency of 3.78–7.94 GHz with notched band at 4.3–5.9 GHz. This result is very useful to reject IEEE 802.11a based services over the UWB Applications. However, the experimental analysis shows different performances both in the operating pass-band and insertion loss. This difference may be occurred due to the technical reason while conducting filter measurement.
Four designs of substrate integrated waveguide (SIW) filter employing integrated broadside-coupled complementary split-ring resonators are compared. By changing the orientation of the rings, four types of SIW unit cell are proposed and investigated and it is shown that, for one particular topology, two poles and two zeros can be realised with a single unit cell. Bandpass filters based on the proposed resonators coupled by evanescent-mode SIW sections have been fabricated and tested. The proposed filters have the advantages of compact size, high selectivity and ease of integration.
This letter proposes a novel branch-line resonator to design a fourth-order cross-coupled bandpass filter (BPF). Theoretically, the proposed branch-line resonator plays two crucial roles. First, the arbitrary number transmission zeros can be designed in the stopband of a fourth-order cross-coupled BPF. Second, the required external quality factor can also be designed without an impedance transformer. This study examines a novel fourth-order cross-coupled BPF with a single pair of transmission zeros produced by a cross-coupled mechanism near the passband and five independent designable transmission zeros created by the proposed resonator in the stopband.
eResonator (SIR) is designed and fabricated. The central frequency of the filter is 2.45GHz and the bandwidth is 8%. By using miniaturized open-loop SIR resonator, we design filter based on cross-coupling, input and output external quality factor. A single transmission zero is realized by the cross coupling in the structures, which can improve the skirt selectivity of the filter. The circuit size of a miniaturized open-loop SIR band-pass filter reduces to 50% of the square open-loop resonator band-pass filter. The results of measurements are in good agreement with the full-wave simulation results.
A microstrip HPF with sharp attenuation by using cross-coupling is proposed in this paper. The HPF consists of parallel plate- and gap type- capacitors and inductor lines. The one block of the HPF has two sections of a constant K filter in the bridge T configuration. Thus the one block HPF is first coarsely designed and the performance is optimized by circuit simulator. With the gap capacitor adjusted the proposed HPF illustrates the sharp attenuation characteristics near the cut-off frequency made by cross-coupling between the inductor lines. In order to improve the stopband performance, the cascaded two block HPF is examined. Its measured results show the good agreement with the simulated ones giving the sharper attenuation slope.
A compact planar microstrip ultra-wideband (UWB) bandpass filter (BPF) is presented in this paper. The proposed UWB filter is realised by cascading a high pass filter (HPF) and a low pass filter (LPF). The designed five-pole HPF consists of inter-digital capacitors and short-circuited stubs and has a sharp falling edge at the cutoff frequency. Additional slots are adopted to improve the return loss performance in the pass band. The LPF is realised mainly based on a non-uniform defected ground structure array in the ground. Combining these two structures, a new UWB bandpass filter is fabricated and measured. The measured results show that the proposed BPF has a wide bandwidth from 3.0-10.8 GHz, associated the 40 dB shape factor as low as 1.2. A group delay variation of less than 0.15 ns in the pass band from 3.0-10.8 GHz is obtained. It also achieves a wide stopband with 20 dB attenuation up to 20.0 GHz
Microstrip filters for RF/microwave applications
- S G Hongj
- J Lancasterm
- J. S. G.Hong
Analysis and design of a new miniature microstrip BPF based on metamaterial and dumbbell DGS.
- Ennajiha Nasirib
- Errkika
- B.Nasiri
Design investigation of a novel bandpass filter using trisection open loop resonator.
- Saghlatoonh
- Neshatim
- H.Saghlatoon